1998.5-2002 Dodge 5.9L Cummins Axle & Driveline Parts

Axles and driveline on the 1998.5-2002 Ram 5.9L Cummins

On this generation the Cummins came only in the 2500 and 3500, and the driveline is simple once you know which axles you have. Four-wheel-drive trucks use a Dana 60 front with a 9.75 in ring gear, ball joints, 1480 u-joints and unit bearings. Front engagement on most of these years is the vacuum-operated Center Axle Disconnect (CAD); it was phased out by 2002, and some 2002 trucks got locking hubs instead. Out back, a 2500 with the automatic got a Dana 70 with a 10.5 in ring gear, rated around 7,500 lb GAWR. Every 3500, and any 2500 with a manual transmission, got the full-floating Dana 80 with an 11.25 in ring gear and an axle rating up to 11,000 lb; from 1998 it used a four-pinion Trac-Lok limited slip. Most trucks left the factory with 3.55 gears matched to roughly 31 in tires, with 4.10 as the heavy-tow ratio. The transfer case is a part-time unit with a 2.72:1 low range, and Diesel Hub's maintenance schedule lists ATF+4 for it.

What fails and why

On a truck this age, most driveline complaints are wear items rather than the gears themselves. Front unit bearings wear until the hub clicks when you turn it by hand, and you may see ABS codes or feel wheel play. That usually shows up well over 100,000 miles, and the hubs fight you coming off, worst on the 1994-1999 captive-rotor design. Dana 60 ball joints wear past 100,000 miles too; they add to wander and death wobble, and you'll find them with a pry bar under the tire or by reading uneven tire wear. A vibration that tracks road speed and eases when there's less torque on the driveline points at the two-piece driveshaft's carrier bearing, which is sealed, can't be greased and is a Dodge-only part, or at worn u-joints. If the 4WD won't engage and the HVAC drops to defrost, look for a split vacuum hose at the 4WD shift collar on CAD trucks; other systems that share that vacuum source can act up too.

Stock replacement vs. upgrade

For routine service, stock-style parts do the job: the right gear oil, a fresh gasket or RTV, and the factory cover back on. The common upgrade in this collection is a finned aluminum cover. Mag-Hytec builds covers for the Dana 60, 70 and 80 that add fluid capacity, a dipstick and a drain plug, aimed at towing duty. Fluid is the other lever. Dodge's base spec on the Dana 80 is 80W-90 with 75W-140 as the heavy-duty alternative, and Diesel Hub's maintenance schedule calls for 75W-140 synthetic in all the Dana axles. Bigger work, like ring-and-pinion regears and lockers, goes beyond this collection; owners stepping up to 37 in tires usually want 4.10 to 4.56 gears. Talk to us before you go that deep so every part matches your axle.

What we carry

Start with differential hardware: Mag-Hytec covers for the Dana 60 front, Dana 70 and Dana 80, a BD Diesel Dana 70 rear cover, AFE Street Series and Dana 80 rear covers, MAHLE cover gaskets, and an ATS Diesel Performance drain plug that fits ATS pans and differential covers. For fluid, there's Hot Shot's Secret ADRENALINE and Blue Diamond synthetic gear oils, Lucas Oil synthetic and heavy-duty gear oils, and Royal Purple Max-Gear 75W-140 synthetic. Rounding it out is an XDP vehicle speed sensor with pigtail, listed for 1995-2006 5.9L Cummins trucks. Parts for the rest of the engine and truck are on our Cummins hub.

Fitment notes

The rear axle depends on model and transmission: Dana 70 on 2500 automatics, Dana 80 on 2500 manuals and every 3500. Check the axle tag before ordering rear covers, gaskets or bearings. Front parts only apply to 4x4 trucks, and the front unit bearing and rotor design changed for 2000, with non-captive rotors and different spindles, so order hub parts by model year. If you're going past a cover into axle shafts, sources disagree on whether 2000-2002 Dana 60 fronts went to 32 spline or kept 35, so verify before you buy. On 1998.5-1999 trucks, don't dial in excess caster with adjustable ball-joint sleeves; it can bind the axle and cause axle-shaft seal leaks, a long job on the driver side. Keep caster near 3.5-4 degrees. A 2002 2500 or 3500 is still this platform even though the 1500 changed that year. When in doubt, verify by VIN.

Frequently asked questions

Do I have a Dana 70 or a Dana 80 rear axle?

If it's a 3500, it's a Dana 80. On a 2500 it comes down to the transmission: automatic trucks got the Dana 70 and manual trucks got the Dana 80. Confirm with the axle tag before you buy, because covers and gaskets are listed by axle.

What gear oil goes in a 24-valve Ram's differentials?

Dodge's base spec on the Dana 80 is 80W-90, with 75W-140 as the heavy-duty alternative. Diesel Hub's maintenance schedule goes straight to 75W-140 synthetic for all the Dana axles. If your axle has a limited slip, add limited-slip additive as the owner's manual directs.

How much fluid does the Dana 80 hold?

Either 3.4 or 5.0 quarts depending on the application, and the right way to fill it is to the plug. A Mag-Hytec cover adds capacity, so buy extra fluid when you install one.

What causes a vibration that changes with road speed?

On these trucks, look first at the two-piece driveshaft's carrier bearing and the u-joints. The carrier bearing is sealed, can't be greased, and is a Dodge-specific part. The vibration typically eases when there's less torque going through the driveline.

My 4WD won't engage and the heat only blows on the windshield. Are they related?

They can be. On trucks with the vacuum-operated Center Axle Disconnect, a split hose at the 4WD shift collar can kill 4WD and upset other systems on the same vacuum source, including the HVAC defaulting to defrost. Check the vacuum hoses before you suspect the axle.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.